The subject of the invention is a measuring cell for the continuous determination of the carbon dioxide content of a liquid flowing through a pipe, especially a beverage.
It is known to determine the content of carbon dioxide in beer and other carbonated beverages by analyzing individual samples by chemical or static physical methods. These methods, however, are difficult and they permit no more than a "spot check" of the liquid in question.
It is furthermore known to determine the carbon dioxide content of a liquid continuously by means of a diffusion cell inserted into a pipe line wherein an inert carrier gas is fed into and out of the cell and the carbon dioxide content of the output gas is measured by determining the infrared absorption. This known method, however, is very expensive and contains many sources of error.
It has also become known to continuously determine the carbon dioxide content of a liquid flowing through a pipe by means of an apparatus in which a partial stream of the liquid is carried by a measuring pipe through a measuring cell in which an outgassing of the liquid takes place, a device for measuring the static liquid pressure being provided ahead of the measuring cell, and a device for measuring the temperature and one for measuring the outgassing pressure being provided within the measuring cell, the measurements being transmitted continuously to an evaluating means.
In this known system, the second chamber of a differential pressure meter serves as the measuring cell, while the static liquid pressure is measured in the first chamber of the differential pressure meter. The measurement of the pressure is performed mechanically, and all of the measurements are evaluated and indicated in a mechanical system. The accuracy and speed of measurement achievable by this known system, however, are very limited.